srt-runtime 0.1.0

//! Drift-guard for the spec/field-enum label convention (issue #204).
//!
//! Scans this crate's `src/` for every `pub enum`, subtracts a documented
//! skip-list, and fails if any remaining enum has no `Display` impl. Every
//! non-skipped enum here gets its `Display` from
//! `broadcast_common::impl_spec_display!`, which requires an inherent
//! `name()` — so a present `Display` implies the whole convention is
//! satisfied.

use std::collections::BTreeSet;
use std::fs;
use std::path::Path;

/// Enums that are intentionally **not** spec/field labels:
const SKIP: &[&str] = &[
    "Error",         // structured thiserror error
    "SrtPacket",     // data-carrying ADT (Data/Control payload)
    "ControlPacket", // data-carrying ADT (one variant per control packet struct)
    "AckCif",        // data-carrying ADT (Full/Small/Light field sets)
    "LossListEntry", // data-carrying ADT (Single/Range sequence numbers)
];

fn read_rs(dir: &Path, out: &mut Vec<String>) {
    for entry in fs::read_dir(dir).expect("read src dir") {
        let path = entry.expect("dir entry").path();
        if path.is_dir() {
            read_rs(&path, out);
        } else if path.extension().is_some_and(|x| x == "rs") {
            out.push(fs::read_to_string(&path).expect("read .rs"));
        }
    }
}

/// True if `{prefix}{name}` appears with an identifier boundary (whole name).
fn has_impl(all: &str, prefix: &str, name: &str) -> bool {
    let needle = format!("{prefix}{name}");
    let mut start = 0;
    while let Some(idx) = all[start..].find(&needle) {
        let end = start + idx + needle.len();
        let next = all[end..].chars().next();
        if !matches!(next, Some(c) if c.is_alphanumeric() || c == '_') {
            return true;
        }
        start = end;
    }
    false
}

#[test]
fn every_public_spec_enum_has_a_display_impl() {
    let src = Path::new(env!("CARGO_MANIFEST_DIR")).join("src");
    let mut files = Vec::new();
    read_rs(&src, &mut files);
    let all = files.join("\n");

    let mut enums = BTreeSet::new();
    for line in all.lines() {
        if let Some(rest) = line.trim_start().strip_prefix("pub enum ") {
            let name: String = rest
                .chars()
                .take_while(|c| c.is_alphanumeric() || *c == '_')
                .collect();
            if !name.is_empty() {
                enums.insert(name);
            }
        }
    }

    let missing: Vec<_> = enums
        .iter()
        .filter(|e| !SKIP.contains(&e.as_str()))
        .filter(|e| !has_impl(&all, "Display for ", e) && !has_impl(&all, "impl_spec_display!(", e))
        .cloned()
        .collect();

    assert!(
        missing.is_empty(),
        "pub enum(s) missing a Display impl (issue #204 convention): {missing:?}\n\
         Add `name()` + `broadcast_common::impl_spec_display!(...)`, or add the \
         enum to SKIP if it is not a spec/field label."
    );
}